Gas turbine engine and electrical system

ABSTRACT

A gas turbine engine includes first and second electrical machines coupled to the gas turbine engine, each of the first and second electrical machines electrically coupled to both a primary electrical bus and a secondary electrical bus. The gas turbine includes a first controller configured to control operation of the gas turbine engine, and a second controller coupled to the first controller, the second controller configured to respond to control inputs from the first controller and control an electrical output of the first and second electrical machines to the primary and secondary electrical busses. A converter controller is coupled to an energy storage system, the second controller, the primary electrical bus, and the secondary electrical bus.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 14/135,567 file Dec. 19, 2013, which claimspriority to U.S. Provisional Patent Application Ser. No. 61/780,940filed Mar. 13, 2013, the contents of which are hereby incorporated intheir entirety.

GOVERNMENT RIGHTS

The present application was made with the United States governmentsupport under Contract No. FA8650-09-C-2938, awarded by the UnitedStates Air Force. The United States government has certain rights in thepresent application.

FIELD OF THE DISCLOSURE

The present disclosure relates to gas turbine engines, and moreparticularly to gas turbine engines having electrical systems.

BACKGROUND

Gas turbine engine spools that generate electrical power remain an areaof interest. Some existing systems have various shortcomings, drawbacks,and disadvantages relative to certain applications. Accordingly, thereremains a need for further contributions in this area of technology.

SUMMARY

One embodiment of the present disclosure is a unique gas turbine engine.Another embodiment of the present disclosure is a unique machine. Otherembodiments include apparatuses, systems, devices, hardware, methods,and combinations for gas turbine engines and electrical systems. Furtherembodiments, forms, features, aspects, benefits, and advantages of thepresent application will become apparent from the description andfigures provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and wherein:

FIG. 1 schematically illustrates some aspects of non-limiting example ofa gas turbine engine in accordance with an embodiment of the presentdisclosure.

FIG. 2 schematically illustrates some aspects of a non-limiting exampleof an electrical system employed in conjunction with the gas turbineengine of FIG. 1 in accordance with an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

For purposes of promoting an understanding of the principles of thedisclosure, reference will now be made to the embodiments illustrated inthe drawings, and specific language will be used to describe the same.It will nonetheless be understood that no limitation of the scope of thedisclosure is intended by the illustration and description of certainembodiments of the disclosure. In addition, any alterations and/ormodifications of the illustrated and/or described embodiment(s) arecontemplated as being within the scope of the present disclosure.Further, any other applications of the principles of the disclosure, asillustrated and/or described herein, as would normally occur to oneskilled in the art to which the disclosure pertains, are contemplated asbeing within the scope of the present disclosure.

Referring to the drawings, and in particular FIG. 1, there areillustrated some aspects of a non-limiting example of a gas turbineengine 20 in accordance with an embodiment of the present disclosure. Inone form, engine 20 is a propulsion engine, e.g., an aircraft propulsionengine. In other embodiments, engine 20 may be any other type of gasturbine engine, e.g., a marine gas turbine engine, an industrial orpower generation gas turbine engine, or any aero, aero-derivative ornon-aero derivative gas turbine engine. In one form, engine 20 is a twospool engine having a high pressure (HP) spool (rotor) 24 and a lowpressure (LP) spool (rotor) 26. In other embodiments, engine 20 mayinclude only a single spool, or may include three or more spools, e.g.,may include an intermediate pressure (IP) spool and/or other spoolsand/or partial spools, e.g., on-axis or off-axis compressor and/orturbine stages (i.e., stages that rotate about an axis that is the sameor different than that of the primary spool(s)). In one form, engine 20is a turbofan engine. In other embodiments, engine 20 may be any othertype of gas turbine engine, such as a turboprop engine, a turboshaftengine, a propfan engine, a turbojet engine or a hybrid or combinedcycle engine. As a turbofan engine, LP spool 26 is operative to drive apropulsor 28 in the form of a turbofan (fan) system, which may bereferred to as a turbofan, a fan or a fan system. As a turboprop engine,LP spool 26 powers a propulsor 28 in the form of a propeller system (notshown), e.g., via a reduction gearbox (not shown). As a propfan engine,LP spool 26 powers a propulsor 28 in the form of a propfan. In otherembodiments, propulsor 28 may take other forms, such as one or morehelicopter rotors or tilt-wing aircraft rotors, for example, powered byone or more engines 20 in the form of one or more turboshaft engines.

In one form, engine 20 includes, in addition to fan 28, a bypass duct30, a compressor 32, a diffuser 34, a combustor 36, a high pressure (HP)turbine 38, a low pressure (LP) turbine 40, a nozzle 42A, a nozzle 42B,and a tailcone 46, which are generally disposed about and/or rotateabout an engine centerline 49. In other embodiments, there may be, forexample, an intermediate pressure spool having an intermediate pressureturbine or other turbomachinery components, such as those mentionedabove. In one form, engine centerline 49 is the axis of rotation of fan28, compressor 32, turbine 38 and turbine 40. In other embodiments, oneor more of fan 28, compressor 32, turbine 38 and turbine 40 may rotateabout a different axis of rotation.

In the depicted embodiment, engine 20 core flow is discharged throughnozzle 42A, and the bypass flow from fan 28 is discharged through nozzle42B. In other embodiments, other nozzle arrangements may be employed,e.g., a common nozzle for core and bypass flow; a nozzle for core flow,but no nozzle for bypass flow; or another nozzle arrangement. Bypassduct 30 and compressor 32 are in fluid communication with fan 28. Nozzle42B is in fluid communication with bypass duct 30. Diffuser 34 is influid communication with compressor 32. Combustor 36 is fluidly disposedbetween compressor 32 and turbine 38. Turbine 40 is fluidly disposedbetween turbine 38 and nozzle 42A. In one form, combustor 36 includes acombustion liner (not shown) that contains a continuous combustionprocess. In other embodiments, combustor 36 may take other forms, andmay be, for example, a wave rotor combustion system, a rotary valvecombustion system, a pulse detonation combustion system, a continuousdetonation combustion system and/or a slinger combustion system, and mayemploy deflagration and/or detonation combustion processes.

Fan system 28 includes a fan rotor system 48 driven by LP spool 26. Invarious embodiments, fan rotor system 48 may include one or more rotors(not shown) that are powered by turbine 40. In various embodiments, fan28 may include one or more fan vane stages (not shown in FIG. 1) thatcooperate with fan blades (not shown) of fan rotor system 48 to compressair and to generate a thrust-producing flow. Bypass duct 30 is operativeto transmit a bypass flow generated by fan 28 around the core of engine20. Compressor 32 includes a compressor rotor system 50. In variousembodiments, compressor rotor system 50 includes one or more rotors (notshown) that are powered by turbine 38. Compressor 32 also includes aplurality of compressor vane stages (not shown in FIG. 1) that cooperatewith compressor blades (not shown) of compressor rotor system 50 tocompress air. In various embodiments, the compressor vane stages mayinclude a compressor discharge vane stage and/or one or more diffuservane stages. In one form, the compressor vane stages are stationary. Inother embodiments, one or more vane stages may be replaced with one ormore counter-rotating blade stages.

Turbine 38 includes a turbine rotor system 52. In various embodiments,turbine rotor system 52 includes one or more rotors having turbineblades (not shown) operative to extract power from the hot gases flowingthrough turbine 38 (not shown), to drive compressor rotor system 50.Turbine 38 also includes a plurality of turbine vane stages (not shown)that cooperate with the turbine blades of turbine rotor system 52 toextract power from the hot gases discharged by combustor 36. In oneform, the turbine vane stages are stationary. In other embodiments, oneor more vane stages may be replaced with one or more counter-rotatingblade stages. Turbine rotor system 52 is drivingly coupled to compressorrotor system 50 via a shafting system 54. Turbine 40 includes a turbinerotor system 56. In various embodiments, turbine rotor system 56includes one or more rotors having turbine blades (not shown) operativeto drive fan rotor system 48. Turbine 40 also includes a plurality ofturbine vane stages (not shown in FIG. 1) that cooperate with theturbine blades of turbine rotor system 56 to extract power from the hotgases discharged by turbine 38. In one form, the turbine vane stages arestationary. In other embodiments, one or more vane stages may bereplaced with one or more counter-rotating blade stages. Turbine rotorsystem 56 is drivingly coupled to fan rotor system 48 via a shaftingsystem 58. In various embodiments, shafting systems 54 and 58 include aplurality of shafts that may rotate at the same or different speeds anddirections for driving fan rotor system 48 rotor(s) and compressor rotorsystem 50 rotor(s). In some embodiments, only a single shaft may beemployed in one or both of shafting systems 54 and 58. Turbine 40 isoperative to discharge the engine 20 core flow to nozzle 42A.

During normal operation of gas turbine engine 20, air is drawn into theinlet of fan 28 and pressurized. Some of the air pressurized by fan 28is directed into compressor 32 as core flow, and some of the pressurizedair is directed into bypass duct 30 as bypass flow. Compressor 32further pressurizes the portion of the air received therein from fan 28,which is then discharged into diffuser 34. Diffuser 34 reduces thevelocity of the pressurized air, and directs the diffused core airflowinto combustor 36. Fuel is mixed with the pressurized air in combustor36, which is then combusted. The hot gases exiting combustor 36 aredirected into turbines 38 and 40, which extract energy in the form ofmechanical shaft power to drive compressor 32 and fan 28 via respectiveshafting systems 54 and 58. The hot gases exiting turbine 40 aredischarged through nozzle system 42A, and provide a component of thethrust output by engine 20.

Referring to FIG. 2, some aspects of a non-. limiting example of anelectrical system 70 employed with engine 20 are schematicallyillustrated. In one form, electrical system 70 is configured to bothstart engine 20 and to generate electrical power for one or moreelectrical buses, e.g., primary and secondary electrical bus networks 72and 74 that supply electrical power to one or more flight controlsystems, actuators, weapon systems and/or other systems, e.g., in an airvehicle. In other embodiments, power may be supplied to other electricalbuses for other purposes. In some embodiments, electrical system 70 maynot be configured to start engine 20, but rather, may be configured onlyto generate electrical power for one or more electrical buses.Electrical system 70 includes a controller 80, a controller 82, anelectrical machine 84, an electrical machine 86, an inverter/convertercontroller 88, an inverter/converter controller 90, aninverter/converter controller 92, an inverter/converter controller 94,an energy storage system 96 and a converter controller 98.

In one form, electrical system 70 is configured to supply power inparallel to electrical buses 72 and 74. Electrical system is configuredto regulate the voltage of the electrical bus 72 and/or electrical bus74. In other embodiments, electrical system 70 may be configured tosupply power to a single electrical bus or any number of electricalbuses. The electrical bus voltage may be 270 Vdc, +/−270 Vdc or any acand/or dc voltage suitable for the particular application.

Controller 80 is configured to execute program instructions to controlthe operation of engine 20, and may be, for example, an enginecontroller. In other embodiments, controller 80 may take one or moreother forms. Controller 80 is operative to receive data from variousengine performance and other sensors, actuators and other devices, andto control the operation of engine 20, including fuel flow, the positionof any variable geometry systems and other flow control devices (forengines so equipped), based on demand inputs, e.g., from the flightcontrol system of an aircraft. In one form, controller 80 ismicroprocessor-based and the program instructions are in the form ofsoftware stored in a memory (not shown). However, it is alternativelycontemplated that the controller and program instructions may be in theform of any combination of software, firmware and hardware, includingstate machines, and may reflect the output of discreet devices and/orintegrated circuits, which may be co-located at a particular location ordistributed across more than one location, including any digital and/oranalog devices configured to achieve the same or similar results as aprocessor-based controller executing software or firmware basedinstructions.

Controller 82 is coupled to controller 80. Controller 82 is the primarycontroller that regulates the output of electrical system 70, e.g., inresponse to control inputs from controller 80, and to variations involtage on electrical bus 72 and/or 74, e.g., to maintain a desiredvoltage on electrical buses 72 and/or 74. In particular, controller 82is the primary controller in a primary/secondary relationship withinverter/converter controller 88, inverter/converter controller 90,inverter/converter controller 92, inverter/converter controller 94 andconverter controller 98, whereby inverter/converter controller 88,inverter/converter controller 90, inverter/converter controller 92,inverter/converter controller 94 and converter controller 98 control theoutput of electrical machines 84 and 86, and energy storage system 96,respectively, in response to commands from controller 82. In one form,controller 82 is microprocessor-based and the program instructions arein the form of software stored in a memory (not shown). However, it isalternatively contemplated that the controller and program instructionsmay be in the form of any combination of software, firmware andhardware, including state machines, and may reflect the output ofdiscreet devices and/or integrated circuits, which may be co-located ata particular location or distributed across more than one location,including any digital and/or analog devices configured to achieve thesame or similar results as a processor-based controller executingsoftware or firmware based instructions. In one form, controller 82 isconfigured to control the output of electrical machines 84 and 86, andenergy storage system 96, e.g., via inverter/converter controller 88,inverter/converter controller 90, inverter/converter controller 92,inverter/converter controller 94 and converter controller 98, tominimize parasitic power extraction, increase power generationcapability, increase fault tolerance of system 70, and provideelectrical transient management. Functions of controller 82 include, invarious embodiments, for example, one or more of providing active powermanagement of electrical power generation and storage sources;controlling power transfer between spools, e.g., between HP spool 24 andLP spool 26; power sharing, e.g., as between electrical machines 84 and86; integrated engine 20 feedback to minimize power extraction affects;and regulating bus voltage to maintain consistent voltage duringcontinuous power demands and also during transient power demands. As anon-limiting example, in one study, bus voltage was 270 Vdc, withtransients down to 50 ms power pulses. In one form, controller 82 is astand-alone controller. In other embodiments, controller 82 or itsfunctions may be incorporated into one or more other controllers, e.g.,into controller 80.

Electrical machine 84 is in mechanical communication with HP spool 24,e.g., via shafting system 54. In one form, electrical machine 84 iscoupled to HP spool 24 via a gearbox, such as an accessory gearbox. Inother embodiments, electrical machine 84 may be coupled to HP spool 24via other means, with or without a gearbox and/or shafting. In someembodiments, electrical machine 84 may be mounted directly on HP spool24 or a component of HP spool 24 and/or may be integral with HP spool 24or a component of HP spool 24. In one form, electrical machine 84 is astarter/generator. In other embodiments, electrical machine 84 may takeother forms, and may be, for example, a generator, an alternator and/ora motor. In some embodiments, electrical machine 84 may representmultiple electrical machines in mechanical communication with HP spool24. As a starter/generator, electrical machine 84 is configured toselectively start engine 20, supply mechanical power to HP spool 24 forother reasons, e.g., for power transfer from LP spool 26 or anothersource of electrical power, and to extract power from HP spool 24 andconvert the mechanical power from HP spool 24 into electrical power,e.g., when engine 20 is running, and in some embodiments, when engine 20is windmilling. Electrical machine 84 is configured to supply electricalpower to electrical buses 72 and 74 in power generation mode. Forembodiments wherein electrical machine 84 is a starter generator ormotor generator, electrical machine 84 is configured to supplymechanical power to HP spool 24 based on electrical power supplied toelectrical machine 84 from electrical bus 72 and/or electrical bus 74,depending upon the particular embodiment.

Electrical machine 86 is in mechanical communication with LP spool 26,e.g., via shafting system 58. In one form, electrical machine 86 iscoupled to LP spool 26 via a gearbox. In other embodiments, electricalmachine 86 may be coupled to LP spool 26 via other means, with orwithout a gearbox and/or shafting. In some embodiments, electricalmachine 86 may be mounted directly on LP spool 26 or a component of LPspool 26 and/or may be integral with LP spool 26 or a component of LPspool 26. In one form, electrical machine 86 is a motor/generator. Inother embodiments, electrical machine 86 may take other forms, and maybe, for example, a generator, an alternator and/or a motor. In someembodiments, electrical machine 86 may represent multiple electricalmachines in mechanical communication with LP spool 26 and/or anintermediate pressure (IP) spool of an engine having more than twospools. Alternatively, another electrical machine or group of electricalmachines may be in mechanical communication with such an IP spool andconfigured to perform all or part of the functions of electricalmachines 84 and/or 86, and may also include the correspondinginverter/controller controllers, e.g., electrically arranged similarlyto inverter converter controllers 88, 90, 92 and 94. As amotor/generator, electrical machine 86 is configured to selectivelysupply mechanical power to LP spool 26, e.g., for power transfer from HPspool 24 or another source of electrical power, and to extract powerfrom LP spool 26 and convert the mechanical power from LP spool 26 intoelectrical power, e.g., when engine 20 is running, and in someembodiments, when engine 20 is windmilling. Electrical machine 86 isconfigured to supply electrical power to electrical buses 72 and 74 inpower generation mode. For embodiments wherein electrical machine 86 isa motor generator, electrical machine 86 is configured to supplymechanical power to LP spool 26 based on electrical power supplied toelectrical machine 86 from electrical bus 72 and/or electrical bus 74,depending upon the particular embodiment. By employing electricalmachine 86 to generate electrical power in addition to and in parallelwith electrical machine 84, electrical redundancy is provided, ascompared to engines supplying power via a single electrical machine. Inaddition, by employing electrical machine 86 to generate electricalpower in addition to and in parallel with electrical machine 84,increased power output relative to the use of a single electricalmachine may be achieved in some embodiments.

Inverter/converter controller 88 is electrically coupled to controller82, electrical machine 84 and to electrical bus 72. Inverter/convertercontroller 88 is a power electronic inverter/converter includingcontroller functionality, and is configured to self-regulate and adaptthe power output of electrical machine 84 into a form suitable for useon electrical bus 72. In one form, inverter/converter controller 88 isconfigured to provide electrical power from electrical machine 84 toelectrical bus 72 in parallel with inverter/converter controller 92under the direction of controller 82. In other embodiments,inverter/converter controller 88 may be configured to provide electricalpower from a plurality of electrical machines to electrical bus 72 underthe direction of controller 82. Similarly, in some embodiments,inverter/converter controller 88 may be configured to provide electricalpower to a plurality of electrical machines from electrical bus 72 underthe direction of controller 82.

Inverter/converter controller 90 is electrically coupled to controller82, electrical machine 84 and to electrical bus 74. Inverter/convertercontroller 90 is a power electronic inverter/converter includingcontroller functionality, and is configured to self-regulate and adaptthe power output of electrical machine 84 into a form suitable for useon electrical bus 74. In one form, inverter/converter controller 90 isconfigured to provide electrical power from electrical machine 84 toelectrical bus 74 in parallel with inverter/converter controller 94under the direction of controller 82. In other embodiments,inverter/converter controller 90 may be configured to provide electricalpower from a plurality of electrical machines to electrical bus 74 underthe direction of controller 82. Similarly, in some embodiments,inverter/converter controller 90 may be configured to provide electricalpower to a plurality of electrical machines from electrical bus 74 underthe direction of controller 82.

Inverter/converter controller 92 is electrically coupled to controller82, electrical machine 86 and to electrical bus 72. Inverter/convertercontroller 92 is a power electronic inverter/converter includingcontroller functionality, and is configured to self-regulate and adaptthe power output of electrical machine 86 into a form suitable for useon electrical bus 72. In one form, inverter/converter controller 92 isconfigured to provide electrical power from electrical machine 86 toelectrical bus 72 in parallel with inverter/converter controller 88under the direction of controller 82. In other embodiments,inverter/converter controller 92 may be configured to provide electricalpower from a plurality of electrical machines to electrical bus 72 underthe direction of controller 82. Similarly, in some embodiments,inverter/converter controller 92 may be configured to provide electricalpower to a plurality of electrical machines from electrical bus 72 underthe direction of controller 82.

Inverter/converter controller 94 is electrically coupled to controller82, electrical machine 86 and to electrical bus 74. Inverter/convertercontroller 94 is a power electronic inverter/converter includingcontroller functionality, and is configured to self-regulate and adaptthe power output of electrical machine 86 into a form suitable for useon electrical bus 74. In one form, inverter/converter controller 94 isconfigured to provide electrical power from electrical machine 86 toelectrical bus 74 in parallel with inverter/converter controller 90under the direction of controller 82. In other embodiments,inverter/converter controller 94 may be configured to provide electricalpower from a plurality of electrical machines to electrical bus 74 underthe direction of controller 82. Similarly, in some embodiments,inverter/converter controller 94 may be configured to provide electricalpower to a plurality of electrical machines from electrical bus 74 underthe direction of controller 82.

Energy storage system 96 is an electrical energy storage device. In oneform, energy storage system 96 is a battery. In some embodiments,multiple batteries may be employed. In other embodiments, energy storagesystem 96 may take one or more other forms in addition to or in place ofbattery storage, for example and without limitation, one or moreultra-capacitors, one or more flywheel storage systems and/or otherenergy storage systems. Energy storage system 96 is coupled toelectrical bus 72 and electrical bus 74 via converter controller 98.Energy storage system 96 is configured to selectively supply power toelectrical bus 72 and electrical bus 74 and absorb power from electricalbus 72 and electrical bus 74, via converter controller 98. In otherembodiments, energy storage system 96 may be configured to supply and/orabsorb power to/from only electrical bus 72 or electrical bus 74. In oneform, energy storage system 96 is configured to absorb transient loadsfrom electrical bus 72 and electrical bus 74. The electrical energycapacity and power absorption rates may vary with the needs of theapplication, e.g., the anticipated transient loads on electrical bus 72and electrical bus 74. In some embodiments, energy storage system 96 maybe configured to absorb transient loads from electrical bus 72 orelectrical bus 74. In one form, energy storage system 96 is configuredto provide energy storage for regenerative energy from electrical system70, and to provide supplemental power to augment the output ofelectrical machines 84 and 86. In other embodiments, energy storagesystem 96 may not be so configured, or may be so configured only inpart. By employing energy storage system 96 to supply electrical powerin addition to and in parallel with electrical machines 84 and 86,additional electrical redundancy is provided. In addition, power mayalso be supplied from energy storage system 96 to one or both ofelectrical buses 72 and 74 in the event of a failure that renders one orboth of electrical machines 84 and 86 unable to supply power to one orboth of electrical buses 72 and 74.

Converter controller 98 is electrically coupled to controller 82, energystorage system 96 and to electrical bus 72 and electrical bus 74.Converter controller 98 a power electronic converter includingcontroller functionality, and is configured to self-regulate and adaptthe power output of energy storage system 96 into a form suitable foruse on electrical bus 72 and electrical bus 74; and adapt the poweroutput of electrical bus 72 and electrical bus 74 into a form suitablefor storage in energy storage system 96. In one form, convertercontroller 98 is configured to control the amount of electrical powersupplied to electrical bus 72 and electrical bus 74 from energy storagesystem 96 under the direction of controller 82. In other embodiments,converter controller 98 may be configured to control the amount ofelectrical power supplied to electrical bus 72 or electrical bus 74 fromenergy storage system 96 under the direction of controller 82. In oneform, converter controller 98 is configured to control the amount ofelectrical power received from electrical bus 72 and electrical bus 74and supplied to energy storage system 96 for absorption by energystorage system 96 under the direction of the controller 82. In otherembodiments, converter controller 98 may be configured to control theamount of electrical power received from electrical bus 72 or electricalbus 74 and supplied to energy storage system 96 for absorption by energystorage system 96 under the direction of controller 82. In one form,converter controller 98 is considered a part of energy storage system96. In other embodiments, converter controller 98 may disposed elsewhereor otherwise not considered a part of energy storage system 96. In someembodiments, energy storage system 96 is continuously connected toelectrical buses 72 and 74 via converter controller 98, but is onlyenabled during emergency “power fill-in” periods, i.e., is only usedintermittently. In other embodiments, energy storage system 96 may beemployed continuously, or only during designated events.

During use, engine 20 is started by electrical machine 84. In one form,the power to start engine 20 is supplied by electrical buses 72 and 74.In other embodiments, other power sources may be employed. After beingstarted, both electrical machines 84 and 86 generate electrical powerduring typical engine operation, and supply the electrical power toelectrical buses 72 and 74 via respective inverter/converter controllers88, 90, 92 and 94. In some embodiments, energy storage system 96 may beused to supply power to one or both of electrical buses 72 and 74 duringperiods of high demand, e.g., peak demand periods. In such embodiments,the size of one or both of electrical machines 84 and 86 may be reduced,since they would not be required to be sized to handle the peak demandloads. In such embodiments, the capacity of energy storage system 96 maybe determined based on anticipated loads that are in excess of theoutput capacity of electrical machines 84 and 86, e.g., under particularoperating conditions.

In some embodiments, electrical system 70 is configured to performtransient load management, e.g., during the operation of engine 20.Generally, electrical transients propagated through the bus network,e.g., one or both of electrical buses 72 and 74, e.g., resulting fromthe use of components supplied with power from electrical buses 72and/or 74, may have adverse impact on other components, includingreducing component life. Adversely affected components may includeengine components, e.g., a generator, accessory gearbox used to drivethe generator or one or more other components disposed mechanically orelectrically between the electrical bus and the engine spool or shaftthat supplies mechanical power to the generator. Damage to mechanicalcomponents under such conditions would result from the mechanical loadsimposed from the generator in response to the electrical transients.Other adversely affected components may include any or all othercomponents that are coupled to the electrical bus, even those componentsthat are unrelated to the engine. Accordingly, in some embodiments,energy storage system 96 and converter controller 98 are configured toabsorb electrical transients from electrical buses 72 and 74 in order toperform transient load management, hence reducing or eliminating theadverse impact of the electrical transients. In some embodiments,accumulator 96 and converter controller 98 may be configured to absorbelectrical transients from electrical bus 72 or electrical bus 74 inorder to perform transient load management.

In some embodiments, through the use of energy storage system 96, powercan be stored and used during times where it would be disadvantageous toextract power (e.g., for electrical power generation) from engine 20through one or both of electrical machines 84 and 86, e.g., during highthrust mission scenarios, such as take-off conditions, certainmaneuvering conditions and/or other flight operations.

In some embodiments, active power management (APM) and reduced orminimized negative engine impact are provided by electrical system 70.In one form, APM functionality is provided via controller 82. Forexample, in some embodiments, controller 82 manages power flow throughelectrical system 70 power components, e.g., electrical machine 84,electrical machine 86, inverter/converter controller 88,inverter/converter controller 90, inverter/converter controller 92,inverter/converter controller 94, energy storage system 96 and convertercontroller 98. In some embodiments, controller 82 is configured toselect the appropriate component that minimizes the impact of electricalsystem 70 components on engine 20, e.g., minimizes impact on theoperation of engine 20. Aspects of engine 20 operation for impactconsideration include parasitic power off-take, which affects specificfuel consumption (SFC), surge margin (high pressure spool 24, lowpressure spool 26 and any intermediate pressure spool for engines soequipped), inter-turbine temperature (ITT), and net thrust, to name afew examples. At different segments of the platform mission, it may bemore advantageous to extract power from HP spool 24, whereas at othertimes it may be more advantageous to extract power from LP spool 26, andin other situations, it may be more advantageous to extract power fromboth HP spool 24 and LP spool 26. Controller 82 directs power extractionduring differing mission segments depending on the positive affect itwould have on the engine. For instance, it is sometimes advantageous toextract power form the LP shaft instead of the HP shaft. Under suchcircumstances, controller 82 would engage electrical machine 86 toprovide power to the bus network(s), e.g., electrical buses 72 and 74instead of using electrical machine 84 to supply the power. In someembodiments, energy storage system 96 (and converter controller 98) isconfigured to supply power to electrical bus 72 and/or electrical bus 74during high thrust operations of the gas turbine engine. For example,during mission segments where engine 20 must perform high thrustmaneuvers that necessitate a decoupling of parasitic power off-takelosses from the engine, controller 82 would direct the energy storagesystem 96 to provide the bulk of the power necessary to the busnetwork(s), and direct either electrical machine 84 or electricalmachine 86 (whichever one has less of a negative engine impact) toprovide the remaining power amount (if energy storage system 96 wasn'tsufficient to power the loads on the electrical bus(es)).

In some embodiments, electrical system 70, in particular controller 82,electrical machine 84, electrical machine 86, first inverter/convertercontroller 88, inverter/converter controller 90, inverter/convertercontroller 92 and inverter/converter controller 94 are configured forvariable power sharing as between the electrical machine 84 and theelectrical machine 86 when supplying electrical power to electrical bus72 and/or electrical bus 74. In some embodiments, electrical system 70is configured to perform multi-shaft (or multi-spool) power sharing.Controller 82 enables power sharing, whereby both electrical machines 84and 86 provide power to a shared bus network (e.g., electrical bus 72and/or electrical bus 74) at the same time. In addition, under thedirection of controller 82, electrical machines 84 and 86 may providepower to the electrical buses (e.g., electrical bus 72 and electricalbus 74) at differing power levels, while maintaining bus voltage,yielding variable power sharing. For example, under the direction ofcontroller 82 electrical machines 84 and 86 can provide variable powerlevels to one or more common bus networks buses (e.g., electrical bus 72and electrical bus 74), such as a power split of 75% of the electricalload being supplied by electrical machine 86 and 25% of the electricalload being supplied by electrical machine 84. The load split during thepower sharing operations may change on the fly, e.g., based on engineoperating requirements and electrical load requirements. In variousembodiments and/or various operating conditions, the total electricalload supplied to the electrical bus(es) may vary at any point in timebetween being supplied in the amount of 0-100% by electrical machine 84,with the balance being supplied in the amount of 100%-0, being suppliedby electrical machine 86, for a total of 100% supplied to the electricalbus(es) by electrical machine 84 and/or electrical machine 86, yieldingdynamic variable power sharing. In other embodiments, power sharing maytake place between more than two electrical machines.

In some embodiments, electrical system 70 is configured to performenergy storage charging. Through system 70 and interactive controller82, energy storage system 96 can be charged through multiple sources,e.g., depending upon the embodiment. Energy storage system 96 isbidirectional capable, thereby being able to absorb power off of the busnetwork (e.g., electrical buses 72 and/or 74, e.g., at 270 Vdc). Energystorage system 96 is configured to absorb the excess load from thebus(es) via converter controller 98 as the network bus voltage builds inexcess of rated voltage, thereby charging energy storage system 96.Excess rated power may be intentionally introduced if the platformactuators were to generate power by closing/opening and the power wasput onto the bus allowing for regenerative energy. Also, electricalmachines 84 and/or 86 could provide power in excess of that needed bythe bus network loads, wherein energy storage system 96 could absorb theexcessive load, thereby charging energy storage system 96. The selectionof which method (electrical machines 84 and/or 86 and/or actuator powerregeneration and/or other charging schemes) may be monitored and/orcontrolled by controller 82.

In some embodiments, electrical system 70 is configured to transferpower between HP spool 24 and LP spool 26. More particularly, electricalsystem 70 is configured for shaft power transfer; i.e., power transferbetween engine 20 spools, e.g., HP spool 24, LP spool 26 and also an IPspool for engines so equipped. During aggressive aircraft maneuvers orduring high power electrical power off-take, power transfer between HPspool 24 and LP spool 26 has shown an increase in HP surge margin andSFC at turbine engine off-design operating points. Power transferbetween engine shafts also has potential benefits of maintaining enginecompressor operating points (i.e. increased efficiency), increased lifeexpectancy of compressor outlet blades, increased engine thrustresponse, and fan windmill assist start. Shaft power transfer refers totransferring power between HP and LP spools 24 and 26 (and between oneor both spools 24 and 26 and an IP spool for engines so equipped)whereby power is transferred from one spool to the other. Power transferis achieved by operating one or more electrical machines on one spool asa motor and one or more electrical machines on another spool as agenerator, e.g., with the motor(s) being powered by the generator(s),thereby transferring power from one spool to the other. Power could betransferred from LP spool 26 to HP spool 24 under some circumstances,for example, a windmill start; and in other scenarios, power could betransferred from HP spool 24 to LP spool 26, e.g., under maximum takeoffthrust conditions. In some embodiments, e.g., a multi-engine platform,power transfer may include transferring shaft power from one or morespools of one engine to one or more spools of one or more other engines.

In some embodiments, online optimization may be performed: Controller 82maintains interconnections with engine 70, electrical machine 84,electrical machine 86, and energy storage system 96. Engine 70performance is a key input to the controller 82, where power extractionfrom any parasitic power extraction source (electrical machine 84,electrical machine 86, and in embodiments so equipped, an electricalmachine on an IP spool, etc.) can negatively affect engine 20performance (surge margin, fuel efficiency, transient performance,etc.). Controller 82 monitors the engine performance feedback andperforms online optimization of all available power sources to providethe required power from the ‘best’ source or combination of sources. Thedefinition of “best” may include engine performance to maximize surgemargin, fuel efficiency, etc; however, “best” will also include powerquality, bus stability, transient handling, and combining power sourcesto a common bus.

In some embodiments, an intermediate pressure (IP) spool may be employedin addition to HP spool 24 and LP spool 26, such as in a three-spoolengine. It will be understood that, just as LP spool 26 and HP spool 24each include at least one electrical machine operative to function as amotor/generator, the same could hold true for the IP spool, which mayinclude at least one electrical machine configured to operate as amotor/generator. The appropriate number of inverter/convertercontrollers associated with the motor/generator(s) if the IP spool wouldalso be included, e.g., similar to those employed for electricalmachines 84 and 86. Accordingly, embodiments described herein withrespect to a two-spool engine are applicable to three-spool engines.

In some embodiments, a DEW (Directed Energy Weapon(s)) dedicated bus maybe employed. It is contemplated that electrical buses 72 and 74 couldboth be positive voltage buses, e.g., 270 Vdc, although in otherembodiments, one of the two buses may be +270 Vdc, whereas the other maybe −270 Vdc. In some embodiments, it is contemplated that a DEWDedicated Bus may be employed: The ±270 VDC bus can be further modifiedto include a dedicated DEW bus network at a higher voltage than 270 VDCor even higher than ±270 VDC. For example, in some embodiments, adedicated DEW bus at a much higher voltage may be required due to massand volume limitations of distribution cables, e.g., a 1 kv bus voltage.

Embodiments of the present disclosure include a gas turbine engine,comprising: a high pressure spool; a low pressure spool; and anelectrical system configured to supply power in parallel to a firstelectrical bus and a second electrical bus, including: a firstcontroller configured to control operation of the gas turbine engine; asecond controller coupled to the first controller; a first electricalmachine in mechanical communication with the high pressure spool; asecond electrical machine in mechanical communication with the lowpressure spool; a first inverter/converter controller coupled to thesecond controller, the first electrical machine and one the firstelectrical bus and the second electrical bus, and configured to provideelectrical power to the one the first electrical bus and the secondelectrical bus under direction of the second controller; a secondinverter/converter controller coupled to the second controller, thesecond electrical machine, the other of first electrical bus and thesecond electrical bus, and configured to provide electrical power to theother of the first electrical bus and the second electrical bus underthe direction of the second controller; an energy storage systemconfigured to supply power to and absorb power from at least one of thefirst electrical bus and the second electrical bus; and a convertercontroller coupled to the energy storage system, the second controllerand the at least one of the first electrical bus and the secondelectrical bus, wherein the converter controller is configured tocontrol the amount of electrical power supplied to the at least one ofthe first electrical bus and the second electrical bus from the energystorage system under the direction of the second controller; and tocontrol the amount of electrical power received from the at least one ofthe first electrical bus and the second electrical bus and supplied tothe energy storage system under the direction of the second controller.

In a refinement, the gas turbine engine of further comprises a thirdinverter/converter controller coupled to the second controller, thefirst electrical machine and the other of first electrical bus and thesecond electrical bus, and configured to provide electrical power to theother of first electrical bus and the second electrical bus in parallelwith the second inverter/converter controller under the direction of thesecond controller.

In another refinement, the gas turbine further comprises a fourthinverter/converter controller coupled to the second controller, thesecond electrical machine, and the one the first electrical bus and thesecond electrical bus, and configured to provide electrical power to theone the first electrical bus and the second electrical bus in parallelwith the first inverter/converter controller under direction of thesecond controller.

In yet another refinement, the first electrical machine is astarter/generator.

In still another refinement, the energy storage system is configured toabsorb transient loads on the first electrical bus and/or the secondelectrical bus.

In yet still another refinement, the second controller, the firstelectrical machine, the second electrical machine, the firstinverter/converter controller and the second inverter/convertercontroller are configured for variable power sharing as between thefirst electrical machine and the second electrical machine whensupplying electrical power to the first electrical bus and/or the secondelectrical bus.

In a further refinement, the electrical system is configured to regulatea voltage of the first electrical bus and/or the second electrical bus.

In a yet further refinement, the electrical system is configured totransfer power between the high pressure spool and the low pressurespool.

In a still further refinement, the energy storage system is configuredto supply power to the first electrical bus and the second electricalbus during high thrust operations of the gas turbine engine.

Embodiments of the present disclosure include a machine, comprising: afirst rotor; a second rotor; and an electrical system configured tosupply power in parallel to an electrical bus, including: a firstcontroller configured to control operation of the machine; a secondcontroller coupled to the first controller; a first electrical machinein mechanical communication with the first rotor; a second electricalmachine in mechanical communication with the second rotor; a firstinverter/converter controller coupled to the second controller, thefirst electrical machine and the electrical bus, and configured toprovide electrical power to the electrical bus under the direction ofthe second controller; a second inverter/converter controller coupled tothe second controller, the second electrical machine and the electricalbus, and configured to provide electrical power to the electrical busunder the direction of the second controller; an energy storage systemconfigured to supply power to and absorb power from the electrical bus;and a converter controller coupled to the energy storage system, thesecond controller and the electrical bus, wherein the convertercontroller is configured to control the amount of electrical powersupplied to the electrical bus from the energy storage system under thedirection of the second controller; and configured to control the amountof electrical power received from the electrical bus and supplied to theenergy storage system under the direction of the second controller.

In a refinement, the machine further comprises a thirdinverter/converter controller coupled to the second controller, thefirst electrical machine and the electrical bus, and configured toprovide electrical power to the electrical bus in parallel with thefirst inverter/converter controller under direction of the secondcontroller.

In a another refinement, the machine further comprises a fourthinverter/converter controller coupled to the second controller, thesecond electrical machine and the electrical bus, and configured toprovide electrical power to the electrical bus in parallel with thesecond inverter/converter controller under direction of the secondcontroller.

In yet another refinement, the first electrical machine is astarter/generator.

In still another refinement, the energy storage system is configured toabsorb transient loads on the electrical bus.

In yet still another refinement, the second controller, the firstelectrical machine, the second electrical machine, the firstinverter/converter controller and the second inverter/convertercontroller are configured for variable power sharing as between thefirst electrical machine and the second electrical machine whensupplying electrical power to the electrical bus.

In a further refinement, the electrical system is configured to regulatea voltage of the electrical bus.

In a yet further refinement, the electrical system is configured totransfer power between the first rotor and the second rotor.

In a still further refinement, the energy storage system is configuredto supply power to the electrical bus during high output operations ofthe machine.

Embodiments of the present disclosure include a gas turbine engine,comprising: a high pressure spool; a low pressure spool; and means forsupplying power to an electrical bus.

In a refinement, the means for supplying power includes a firstelectrical machine coupled to the high pressure spool for supplyingpower to the electrical bus; a second electrical machine coupled to thelow pressure spool for supplying power to the electrical bus; and anenergy storage system coupled to the electrical bus; wherein the firstelectrical machine, the second electrical machine and the energy storagesystem are configured to supply power simultaneously to the electricalbus; wherein the energy storage system is configured to absorb transientloads from the electrical bus; and wherein the energy storage system isconfigured to be charged by the electrical bus.

While the disclosure has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the disclosure is not to be limited to thedisclosed embodiment(s), but on the contrary, is intended to covervarious modifications and equivalent arrangements included within thespirit and scope of the appended claims, which scope is to be accordedthe broadest interpretation so as to encompass all such modificationsand equivalent structures as permitted under the law. Furthermore itshould be understood that while the use of the word preferable,preferably, or preferred in the description above indicates that featureso described may be more desirable, it nonetheless may not be necessaryand any embodiment lacking the same may be contemplated as within thescope of the disclosure, that scope being defined by the claims thatfollow. In reading the claims it is intended that when words such as“a,” “an,” “at least one” and “at least a portion” are used, there is nointention to limit the claim to only one item unless specifically statedto the contrary in the claim. Further, when the language “at least aportion” and/or “a portion” is used the item may include a portionand/or the entire item unless specifically stated to the contrary.

What is claimed is:
 1. A method of generating power in a gas turbineengine, comprising: coupling a first electrical machine in parallel toboth a primary electrical bus and to a secondary electrical bus via afirst pair of inverter/converter controllers, the first pair ofinverter/converter controllers comprising a first inverter/convertercontroller and a second inverter/converter controller, the firstinverter/converter controller coupled to the primary electrical bus, thesecond inverter/converter controller coupled to the secondary electricalbus, the first electrical machine being coupled to the gas turbineengine; coupling a second electrical machine in parallel to both theprimary electrical bus and to the secondary electrical bus via a secondpair of inverter/converter controllers, the second pair ofinverter/converter controllers comprising a third inverter/convertercontroller and a fourth inverter/converter controller, the thirdinverter/converter controller coupled to the primary electrical bus, thefourth inverter/converter controller coupled to the secondary electricalbus, the second electrical machine being coupled to the gas turbineengine; configuring a first controller to receive data from the gasturbine engine to control operation of the gas turbine engine; couplinga second controller to the first controller; configuring the secondcontroller to control an electrical output of the first and secondelectrical machines to the primary and secondary electrical busses;coupling a converter controller to an energy storage system, the secondcontroller, the primary electrical bus, and the secondary electricalbus; and configuring the converter controller to control an amount ofelectrical power, under direction from the second controller, passingbetween the energy storage system and the primary and secondaryelectrical busses.
 2. The method of claim 1, further comprising couplingthe first electrical machine to a high pressure spool of the gas turbineengine, and coupling the second electrical machine to a low pressurespool of the gas turbine engine.
 3. The method of claim 2, wherein thefirst electrical machine is one of a generator, an alternator, or amotor, and is in mechanical communication with the high pressure spool.4. The method of claim 1, wherein at least one of the first electricalmachine or the second electrical machine is a starter/generatorconfigured to selectively start the gas turbine engine.
 5. The method ofclaim 4, wherein each of the first and second electrical machines is astarter/generator, the first electrical machine being coupled to a highpressure spool of the gas turbine engine, and the second electricalmachine being coupled to a low pressure spool of the gas turbine engine.6. The method of claim 1, wherein the second controller controls each ofthe first inverter/converter controller and the third inverter/convertercontroller to self-regulate and adapt power output of the first andsecond electrical machines to the primary electrical bus.
 7. The methodof claim 1, wherein the second controller, the first electrical machine,the second electrical machine, the first inverter/converter controller,the second inverter/converter controller, the third inverter/convertercontroller, and the fourth inverter/converter controller are configuredfor variable power sharing.
 8. The method of claim 1, wherein the energystorage system is configured to absorb transient loads on the primaryelectrical bus and the secondary electrical bus.
 9. An electrical systemcoupled to a gas turbine engine, and to a primary electrical bus and asecondary electrical bus, the electrical system comprising: a firstelectrical machine and a second electrical machine, the first and secondelectrical machines coupled to the gas turbine engine, the firstelectrical machine electrically coupled in parallel to both the primaryelectrical bus and to the secondary electrical bus via a first pair ofinverter/converter controllers, and the second electrical machineelectrically coupled in parallel to both the primary electrical bus andto the secondary electrical bus via a second pair of inverter/convertercontrollers; a first controller configured to control operation of thegas turbine engine; a second controller coupled to the first controller,the second controller configured to respond to control inputs from thefirst controller and control an electrical output of the first andsecond electrical machines to the primary and secondary electricalbusses; an energy storage system; and a converter controller coupled tothe energy storage system, the second controller, the primary electricalbus, and the secondary electrical bus; wherein the converter controlleris configured to control an amount of electrical power, under directionfrom the second controller, passing between the energy storage systemand at least one of the primary and secondary electrical busses, whereinthe first pair of inverter/converter controllers comprises a firstinverter/converter controller and a second inverter/convertercontroller, the first inverter/converter controller coupled to theprimary electrical bus, the second inverter/converter controller coupledto the secondary electrical bus, and wherein the second pair ofinverter/converter controllers comprises a third inverter/convertercontroller and a fourth inverter/converter controller, the thirdinverter/converter controller coupled to the primary electrical bus, thefourth inverter/converter controller coupled to the secondary electricalbus.
 10. The electrical system of claim 9, wherein: the energy storagesystem is configured to absorb transient loads on the primary electricalbus and the secondary electrical bus, and the second controller, thefirst electrical machine, the second electrical machine, the firstinverter/converter controller, the second inverter/converter controller,the third inverter/converter controller, and the fourthinverter/converter controller are configured for variable power sharing.11. A gas turbine engine, comprising: a low pressure spool; a highpressure spool; a first electrical machine and a second electricalmachine, the first and second electrical machines being coupled to thegas turbine engine, each of the first and second electrical machineselectrically coupled to both a primary electrical bus and a secondaryelectrical bus, the first electrical machine coupled in parallel to boththe first primary electrical bus and to the secondary electrical bus viaa first pair of inverter/converter controllers, and the secondelectrical machine coupled in parallel to both the primary electricalbus and to the secondary electrical bus via a second pair ofinverter/converter controllers; a first controller configured to controloperation of the gas turbine engine; a second controller coupled to thefirst controller, the second controller configured to respond to controlinputs from the first controller and control an electrical output of thefirst and second electrical machines to the primary and secondaryelectrical busses; and a converter controller coupled to an energystorage system, the second controller, the primary electrical bus, andthe secondary electrical bus, wherein the converter controller isconfigured to control an amount of electrical power passing between theenergy storage system and at least one of the primary and secondaryelectrical busses in response to an input from the second controller,wherein the first pair of inverter/converter controllers comprises afirst inverter/converter controller and a second inverter/convertercontroller, the first inverter/converter controller coupled to theprimary electrical bus, the second inverter/converter controller coupledto the secondary electrical bus, and wherein the second pair ofinverter/converter controllers comprises a third inverter/convertercontroller and a fourth inverter/converter controller, the thirdinverter/converter controller coupled to the primary electrical bus, thefourth inverter/converter controller coupled to the secondary electricalbus.
 12. The gas turbine engine according to claim 11, wherein the firstelectrical machine is coupled to the high pressure spool of the gasturbine engine, and the second electrical machine is coupled to the lowpressure spool of the gas turbine engine.
 13. The gas turbine engineaccording to claim 11, wherein the first electrical machine is one of agenerator, an alternator, or a motor, and is in mechanical communicationwith the high pressure spool.
 14. The gas turbine engine according toclaim 11, wherein at least one of the first electrical machine or thesecond electrical machine is a starter/generator configured toselectively start the gas turbine engine.
 15. The gas turbine engineaccording to claim 11, wherein the first electrical machine is a firststarter/generator coupled to the high pressure spool, the secondelectrical machine is a second starter/generator coupled to the lowpressure spool, and the first starter/generator is configured toselectively start the gas turbine engine.
 16. The gas turbine engineaccording to claim 11, wherein the second controller controls each ofthe first inverter/converter controller and the third inverter/convertercontroller to self-regulate and adapt power output of the first andsecond electrical machines to the primary electrical bus.
 17. The gasturbine engine according to claim 11, wherein the second controller, thefirst electrical machine, the second electrical machine, the firstinverter/converter controller, the second inverter/converter controller,the third inverter/converter controller, and the fourthinverter/converter controller are configured for variable power sharing.